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Annals of the ICRP

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ICRP PUBLICATION 1XX

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Radiological Protection from Cosmic Radiationin Aviation

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Editor-in-Chief

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C.H. CLEMENT

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N. HAMADA

Associate Editor

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Authors on behalf of ICRP
J. Lochard, J-F. Bottollier-Depois, W. Rühm,
D. T. Bartlett, R. Hunter, H. Yasuda, S. Mundigl

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PUBLISHED FOR

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The International Commission on Radiological Protection

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by

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[Sage logo]
Please cite this issue as ‘ICRP, 201Y. Radiological Protection from Cosmic
Radiation in Aviation. ICRP Publication 1XX, Ann. ICRP 4X (0).’1

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CONTENTSCONTENTS ............................................................................................................................. 2	  EDITORIAL ............................................................................................................................ 3	
  ABSTRACT ............................................................................................................................. 4	  PREFACE ................................................................................................................................ 5	
  MAIN POINTS ........................................................................................................................ 7	  GLOSSARY............................................................................................................................. 9	
  1.	
   INTRODUCTION .......................................................................................................... 13	
  1.1.	
   Background .............................................................................................................. 13	
  1.2.	
   Scope ........................................................................................................................ 14	
  1.3.	
   Structure of the report .............................................................................................. 14	
  2.	
   CHARACTERISTICS OF EXPOSURE FROM COSMIC RADIATION
IN AVIATION ................................................................................................................ 15	
  2.1.	
   Historical background .............................................................................................. 15	
  2.2.	
   Source and pathways ................................................................................................ 15	
  2.3.	
   Solar eruptions ......................................................................................................... 17	
  2.4.	
   Assessment of individual exposure in aircraft ......................................................... 19	
  2.5.	
   Exposure of aircraft crew ......................................................................................... 20	
  2.6.	
   Epidemiological studies of aircraft crew ................................................................. 22	
  3.	
   THE COMMISSION SYSTEM OF PROTECTION FOR PASSENGERS
AND AIRCRAFT CREW............................................................................................... 24	
  3.1.	
   Type of exposure situations and categories of exposure.......................................... 24	
  3.2.	
   Justification of protection strategies ........................................................................ 25	
  3.3.	
   Optimisation of protection ....................................................................................... 26	
  4.	
   IMPLEMENTATION OF THE SYSTEM OF PROTECTION ..................................... 28	
  4.1.	
   Protective actions ..................................................................................................... 28	
  4.2.	
   Graded approach ...................................................................................................... 28	
  4.3.	
   Protection of embryo and fetus ................................................................................ 31	
  4.4.	
   Information of the general public and stakeholder engagement .............................. 31	
  5.	
   CONCLUSION ............................................................................................................... 33	
  APPENDIX A.	
  Cosmic radiation exposure associated withselected flightroutes34	
  
REFERENCES....................................................................................................................... 35	
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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCEEDITORIAL

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To be drafted

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ABSTRACT

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Radiological protection from cosmic radiationin aviation

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ICRP Publication 1XX

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Approved by the Commission in Month 201X

Abstract–In this report, the Commission provides updated guidance on theradiological protection from cosmic radiation in aviation taking into account thecurrent ICRP system of radiological protection, the latest available data on
exposures in aviation and the experience gained worldwide in their management.
The report describes the origins of cosmic radiation, how it exposes passengers andaircraft crew, the basic radiological protection principles that apply to this existing
exposure situation, and the available protective actions. For the implementation of
the optimisation principle, the Commission recommends a graded approach
proportionate with the level of exposure that may be received by individuals. The
objective is to keep the exposure of the most exposed individuals to reasonablelevels. The Commission also recommends that information be disseminated to raiseawareness about cosmic radiation, and to support informed decisions among
concerned stakeholders.
© 201X ICRP. Published by SAGE.
Keywords: Cosmic radiation; Aviation; Aircraft crew; Frequent flyers; Gradedapproach4

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PREFACE

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“Well, I made it!” were the first words of aviator Charles Lindbergh after the Spiritof St. Louis touched down on Le Bourget airport after flying 5,800 kilometres fromLong Island (The New York Times, 21 May 1924). The observers of the timeemphasised the courage of the pioneer against the cold, the weather conditions andthe tiredness – but no one talked about radiation exposure! And for good reason.
Only a handful of scientists were aware of the phenomenon at that time. This
pioneering performance opened the way for transcontinental flights. Since the flightof Charles Lindbergh, the increase in an airplane’s performance and capacity, lowcost companies and expansion of tourism, have led to large increases in the numberof air passengers: in 2013, around 3.1 billion flight tickets were sold, and this figure
is expected to double by 2030 (International Civil Aviation Organization Air
Navigation Report, 2014). Furthermore, the business jet market continues to grow atabout 4 % per year, and this fleet is expected to double by 2032. This raises thepotential for a significant increase in individual and collective exposure from cosmic
radiation of aircraft crew and passengers keeping in mind that the opportunities andmechanisms to control exposure in aircraft are very limited.
Given this context, the Main Commission of ICRP approved at its meeting in CapeTown, South Africa, in October 2010, the formation of a Task Group, reporting toCommittee 4, to develop guidance on radiological protection against cosmic
radiation exposure in aviation.
The terms of reference of the Task Group was to prepare a publication that describes
and clarifies the application of the 2007 Recommendations (Publication 103) for theprotection of aircraft crew, and also passengers, against cosmic radiation exposure
and particularly frequent flyers. The publication should discuss the type of exposure
situation relevant to the control of exposures in aviation and the appropriate
radiological protection principles to be implemented. Particular attention should begiven to the implementation of the optimisation principle, which is the cornerstoneof the system of radiological protection recommended by the Commission.
The membership of the Task Group was as follows:
J. Lochard (Chair)
D.T. Bartlett

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J-F. Bottollier-Depois
R. Hunter

Corresponding member was:S. Mundigl
Committee 4 Critical Reviewers were:
M. KaiD.A. Cool

Main commission Critical Reviewers were:
H. LiuS. Romanov

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W. Rühm
H. Yasuda

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Acting as Secretary of the Task Group, Sylvain Andresz provided a welcomedscientific assistance during the preparation of this report. Numerous helpfulcomments were also received from Gerhard Frasch, Gérard Desmaris and Frank
Bonnotte. The Task Group would like to thank all of these persons as well as Le
Centre d'étude sur l'Evaluation de la Protection dans le domaine Nucléaire (CEPN,
Fontenay-aux-Roses) for their valuable support.
The Task Group met on 1-2 February 2011 at CEPN premises at Fontenay-auxRoses, France and then worked by correspondence.
The membership of Committee 4 during the period of preparation of this reportwas:(2009-2013)
J. Lochard (Chair)
P. Burns
T. Homma
S. LiuG. Massera
J. Simmonds

W. Weiss (Vice-chair)
P. Carboneras
M. KaiA. Mc-GarryK. Mrabit
A. Tsela

J-F. Lecomte (Secretary)
D.A. Cool
H. LiuS. Magnusson
S. Shinkarev J
W. Zeller(2013-2017)
D.A. Cool (Chair)
F. BochudM. Doruff
M. KaiA. Nisbet
S. Shinkarev

K-W. Cho (Vice-chair)
M. Boyd
E. Gallego
S. LiuD. Oughton
J. TakalaJ-F. Lecomte (Secretary)
A. Canoba
T. Homma
A. McGarry
T. Pather

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MAIN POINTS

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• Cosmic radiation is composed of high-energy particles originating fromspace and from the Sun. Basically, the higher the altitude and the latitude,
the higher the dose rate. Solar eruptions can also affect dose rate of cosmic
radiation. As a result, flying in aircraft increases exposure to cosmic
radiation.

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• Considering that the number of passengers will continue to increase, andaircraft technology will enable planes to fly for longer duration and at
higher altitudes, cumulative exposures of aircraft crew and passengers tocosmic radiation are likely to increase. The Commission therefore considers
that the development and implementation of a protection strategy isjustified.

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• Exposure to cosmic radiation, including solar eruptions, is considered by theCommission as an existing exposure situation.

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• The Commission continues to consider that the exposure of all aircraft
passengers, mainly occasional flyers, but also frequent flyers - for personalneeds or for professional duties - should be regarded as public exposure,and that the exposure of aircraft crew should be treated as occupational
exposure.

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• The Commission also considers that exposure should be maintained as low
as reasonably achievable (ALARA) with a dose reference level selected in
the 5–10 mSv/year range. Selection of the dose reference level should bedone taking into account the level of exposure of the most exposed
individuals who warrant specific attention.

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• For the practical implementation of the protection strategy, the Commission
recommends a graded approach based on the flight frequency of theindividuals.

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o Most passengers in aircraft are occasional flyers and their exposure
to cosmic radiation is considered negligible in the context of their
total radiation exposure. However, the Commission recommends
that general information about cosmic radiation should be madeavailable to all passengers.

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o

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o For the small fraction of frequent flyers for professional duties ofwhich exposures are comparable to those of aircraft crew, theCommission recommends that the requirements for aircraft crew
could be utilised on a case-by-case basis through interactions
between the individual and their organisation, according to theprevailing circumstances.

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For frequent flyers for personal reasons and personal duties, inaddition to the recommendation to provide general information, theCommission encourages the self-assessment of their doses in order, if
desired, to adjust their flight frequency.

For aircraft crew, the Commission recommends that the operating
management:
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218219(i) Individually inform the aircraft crew about cosmic radiation
through an educational programme;

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(ii) Assess the dose of aircraft crew using dedicated calculation
programmes;

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(iii) Record the individual and cumulative dose of aircraft crew.
These data should be made available to the individuals and kept
for sufficient time; and

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(iv) When appropriate, to respect the selected dose reference level
and after consultation with the concerned aircraft crew,
operating management may adjust the flight schedule.

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• Pregnant frequent flyers for personal reasons or professional duties may
adjust their flight frequency to limit the cosmic radiation exposure to theirembryo/fetus. For pregnant aircraft crew, airline management should haveprovisions in place to adjust duties during the remainder of the pregnancy
after its notification.

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• The Commission also recommends that national agencies or airline
companies disseminate information to raise awareness about cosmic
radiation and support informed decisions among all concerned stakeholders,and foster a radiological protection culture for occupationally exposed
individuals.

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCEGLOSSARY

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Categories of exposure
The Commission distinguishes between three categories of radiation
exposure: occupational, public, and medical exposures of patients.

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Cosmic radiation
Cosmic radiation is the ionising radiation consisting of high-energy particles,
primarily atomic nuclei, of extra-terrestrial origin, and the particles generated
by interaction with the atmosphere and other matter.
Primary cosmic radiation is cosmic radiation incident from space and the
Sun at the Earth’s orbit.
Secondary cosmic radiation comprises particles that are created directly or ina cascade of reactions by primary cosmic radiation interacting with theatmosphere or other matter. Important particles with respect to radiologicalprotection and radiation measurements in aircraft are: neutrons, protons,
photons, electrons, positrons, muons, and to a lesser extent, pions and nuclear
ions heavier than protons.
Galactic cosmic radiation (GCR) is cosmic radiation originating outside thesolar system.
Solar cosmic radiation (SCR) is cosmic radiation from the Sun.

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Detriment

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Detriment reflects the total harm to health experienced by an exposed groupand its descendants as a result of the group’s exposure to a radiation source.
It is a multi-dimensional concept. Its principal components are the stochastic
quantities: probability of attributable fatal cancer, weighted probability of
attributable non-fatal cancer, weighted probability of severe heritable effects,
and length of life lost if the harm occurs.

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EmbryoThe human product of conception up to approximately the end of the second
month of pregnancy.

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Emergency exposure situation
Emergency exposure situations are exposure situations resulting from a lossof control of a planned source, or from any unexpected event involving an
uncontrolled source (e.g. a malevolent event). These situations require urgent
and timely actions in order to avoid exposure to occur or to mitigate it.

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EmployerAn organisation, corporation, partnership, firm, association, trust, estate,public or private institution, group, political or administrative entity, or otherpersons designated in accordance with national legislation, with recognised
responsibility, commitment, and duties towards a worker in her or his
employment by virtue of a mutually agreed relationship.

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Existing exposure situations

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Existing exposure situations are exposure situations resulting from sourcesthat already exist when a decision to control the resulting exposure is taken.
This includes natural sources [cosmic radiation, radon and other naturally
occurring radioactive material (NORM)] and man-made sources (long-term
exposure from past practices, accident or radiological events).
Characterisation of exposures is a prerequisite to their control.

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Exposure situation
A situation where a natural or man-made radiation source is transferredthrough various pathways, and the radiation results in exposure of human orbiota.

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Exposure pathway
A route by which radiation or radionuclides can reach humans and cause
exposure.

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Fetus

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The prenatal development stage of a mammal in the later stages ofdevelopment, when it shows all the main recognisable features of the mature
animal, especially a human fetus from the end of the second month of
pregnancy until birth.

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Fluence
Fluence is the number of particles incident on a sphere of cross-sectional area
(e.g. a number of protons per cm-2).

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Frequent flyer
A person who regularly travels by aircraft, for personal reasons or for
professional duties and who might be registered in a frequent flyer
programme. Some frequent flyers may fly at a frequency that is of the orderof magnitude of a typical aircraft crew (e.g. 500 h a year).
Graded approach
A graded approach aims to ensure that the recommendations or requisites
formulated for a group of individuals are commensurate and proportionate
with their level of exposure, considering also the prevailing circumstances.
Justification
The process of determining whether: (1) a planned activity involving
radiation is overall beneficial [i.e. whether the benefits to individuals and tosociety from introducing or continuing the activity outweigh the harm(including radiation detriment) resulting from the activity]; or (2) thedecision to control exposure in an emergency or an existing exposure
situation is likely overall to be beneficial (i.e. whether the benefits toindividuals and to society (including the reduction in radiation detriment)
outweigh its cost and any harm or damage it causes).
Occasional flyer
A person who travels by air from time to time, generally for personal
purposes or professional duties.
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Occupational exposureThis refers to all exposure of workers incurred as a result of their work;
however, because of the ubiquity of radiation, the Commission limits its useof ‘occupational exposure’ to radiation exposures incurred at work as a resultof situations that can reasonably be regarded as being the responsibility ofthe operating management.
Operating management
The person or group of persons that directs, controls, and assesses anorganisation at the highest level. Many different terms are used, including,e.g. chief executive officer, director general, managing director, andexecutive group.
Optimisation of protection
The principle of optimisation of radiological protection is a source-related
process aiming to keep the magnitude of individual doses, the number ofpeople exposed and the likelihood of potential exposure as low as reasonably
achievable (ALARA) below the appropriate dose criteria (constraints orreference level), economic and societal factors being taken into account.

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Planned exposure situations
Planned exposure situations are exposure situations resulting from thedeliberately introduction and operation of sources. Exposures can be
anticipated and fully controlled.

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Principles of protection

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The three basic principles that structure the system of radiological protection:
the principle of justification and the principle of optimisation of protectionthat apply to all controllable exposure situations, and the principle ofapplication of dose limit that applies only to the planned exposure situations.

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Protection action
Action set to protect people from the harm of radiation. Protection actions
are generally those that influence the distance to the source, time of exposure,or the shielding.

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Reference level
In emergency and existing exposure situations, this represents the level ofdose or risk, above which it is judged to be inappropriate to plan to allow
exposures to occur, and below which optimisation of protection should be
implemented. The chosen value for a reference level will depend upon theprevailing circumstances of the exposures under consideration.

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Risk

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Risk relates to the probability that an outcome (e.g. cancer) will occur.
Terms relating to risk are grouped together here:

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Excess relative risk (ERR) is the difference between a risk factor and a
specific outcome. For example, ERR could be the difference between the
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proportion of subjects in a population with a particular disease who were
exposed to a specified risk factor and the proportion of subjects with thatsame disease who were not exposed.

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Relative risk is the ratio of the incidence rate or the mortality rate from thedisease of interest (e.g. cancer) in an exposed population compared to thesame ratio in an unexposed population.

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Solar particle event or solar proton event (SPE)An unusually large fluence of energetic solar particles ejected into space by asolar eruption.

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Sun’s solar wind
The solar wind is a plasma of electrons and protons that boils off the solar
corona and propagates – due to the Sun’s magnetic field – radially from theSun at a velocity on average of 400 km.s-1. The solar wind carries with it arelatively strong and convoluted magnetic field. The Sun’s solar wind is
responsible for the aurora in the Arctic (aurora borealis) and the Antarctic(aurora australis).

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1. INTRODUCTION

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(1) Reaching one’s seat in an aircraft can sometimes be a long journey. Aftercheck-in and police control, one has to undergo airport security control. Radiation
may play a role in this process, being used to screen carry-on luggage, and in somecases, screen individuals themselves. The Commission has recently publishedrecommendations on radiological protection on security screening (ICRP, 2014).
(2) After take-off, as the aircraft climbs to cruising altitude, exposure to cosmic
radiation increases. At typical cruise altitude (>10,000 metres), the dose rate canreach 7 µSv.h-1 (more than 150 times the cosmic radiation exposure at sea level).
The future use of new ultra long-range jets that fly at higher altitudes, and for longer
durations, is estimated to increase the dose by 30–50% compared to current flight
practices.
(3) So far, the Commission has developed a set of recommendations regarding
specifically the radiological protection of aircraft crew and notably pregnant aircraftcrew (ICRP, 1984, 1991). The report intends to review these recommendations but
also consider the exposure of passengers and notably the exposure of the so-calledfrequent flyers travelling for personal reasons or as part of their job.

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1.1. Background

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(4) The Commission first mentioned exposure resulting from flying at highaltitude in Publication 9 (ICRP, 1965). The Commission also noted in paragraph 88
of Publication 26 that “flight at high altitude” can increase the normal exposure tonatural radiation (ICRP, 1977). In paragraph 10 of Publication 39, “flying in thepresent manner” was presented as an example of an existing exposure situation(ICRP, 1984).
(5) The Commission then published its first recommendations on protection
against cosmic radiation exposure in Publication 60 (ICRP, 1991). The Commission
recommended that the personnel involved in the operation of commercial jet aircraft
should be treated as occupationally exposed. As doses are not likely to exceed a predefined value because of the limitations of flight duration, individual monitoring
using dosimeters was not considered necessary. Furthermore, the Commission
pointed out that attention should also be paid to groups such as frequent flyers andcouriers who fly more often than other passengers. There was no mention ofprotection of the remaining passengers.
(6) The Commission subsequently clarified its recommendation in Publication
75 (ICRP, 1997), indicating that because a business traveller could only receive anannual effective dose in the range of 1 mSv (considering about 200 h of flying at
about 5-6 µSv.h-1), the Commission considered that the only group occupationally
exposed to elevated levels of cosmic radiation was aircraft crew. The Commission
also reiterated that there is no need to consider that the use of designated areas inaircraft and the annual effective doses to aircraft crew should be derived from theflying time and typical effective dose rates for the relevant routes, and the control of
exposure mainly ensured by restrictions on the flying time and route selection.
Recently, the International Commission on Radiation Units and Measurements(ICRU) jointly with ICRP published reference and data for the validation of doses
from cosmic radiation to aircraft crew to facilitate international harmonization ofdose assessments for aircraft crew by airlines and their regulators (ICRU, 2010).
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(7)

The report supersedes the previous ICRP recommendations in this area.

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1.2. Scope

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(8) The Commission has recently published recommendations on controlling
exposure from cosmic radiation in space in Publication 123 (ICRP, 2013). The
purpose of the present report is to update and clarify the recommendations of theCommission on controlling exposure from cosmic radiation in aviation. This reporttakes into account the evolution of the general recommendation in Publication 103(ICRP, 2007) for the protection of aircraft crew. The report is intended to enlarge thescope of discussion beyond aircraft crew by considering the exposure of passengers,
notably frequent flyers for personal reasons or professional duties. Given the highproportion of female cabin crew, the report also addresses the topic of the exposureof pregnant women.

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1.3. Structure of the report

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(9) Chapter 2 presents the characteristics of exposure in aviation from cosmic
radiation. It provides a brief description of the source and pathways of exposure aswell as an insight on solar eruptions, routine assessment of levels of exposure andindividual and collective dose data. Chapter 3 describes the Commission’s system ofradiological protection in the context of cosmic radiation exposure in aviation,
including the type of exposure situation, the category of exposure concerned and thebasic principles to be applied. Chapter 4 provides guidance on the implementation of
the system of radiological protection using a graded approach for the various
exposed individuals: occasional flyers, frequent flyers and aircraft crew. A section
addresses the particular situation of the exposure of pregnant passengers and aircraft
crew.

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2. CHARACTERISTICS OF EXPOSURE FROM COSMIC RADIATION IN
AVIATION

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2.1. Historical background

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(10) In September 1859, R.C. Carrington, an English amateur astronomer,
observed a solar eruption with a major mass ejection that travelled towards the Earth.
Telegraph systems failed all over Europe and America, and auroras filled the sky as
far south as the Caribbean. Today, it is known that solar particle or proton events(SPEs), such as this 1859 event, release relatively high-energy particles.
(11) In 1912, V. Hess took a historic balloon ride with three ionisation chambers
to an altitude of 5,300 metres. He found higher levels of radiation as he rose that he
attributed to ionising radiation: four times that on the ground at the flight peak. Hess
ruled out the Sun as the source of radiation by making several balloon ascents atnight and one during a total eclipse. He concluded "the results of my observation are
best explained by the assumption that a radiation of very great penetrating power
enters our atmosphere from above" (Physikalische Zeitschrift, November 1912).
(12) In 1925, R.A. Millikan proved the extra-terrestrial origin of theseradiations and introduced the terms “cosmic rays” and “cosmic radiations”. In thesame year, A. Compton had the idea that cosmic rays were primarily charged
particles.
(13) Commercial supersonic planes were developed during the 1960’s: theTupolev-144 prototype first flight in 1968 and the Concord prototype in 1969. The
high altitude at which supersonic planes cruised (around 19,000 meters) increased
concerns on the exposure of aircraft crew and passengers to cosmic radiation. To
ensure the monitoring of doses, some aircraft crew carried personal dosimeters and aradiometer was installed in the Concord. A special dosimeter was also developed for
the Tupolev-144’s aircraft crew. In the case of a significant increase in radiationlevel (e.g. 300 µSv/h in Tupolev 144), the plane would descend to lower altitude.
This marked the beginning of the routine monitoring of exposure to cosmic radiationin aircraft. Nowadays, the dose from cosmic radiation in aviation is monitored using
computer codes.

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2.2. Source and pathways

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(14) The Earth is exposed continuously to high-energy particles that come fromoutside the solar system – galactic cosmic radiation (GCR) – and from the Sun –solar cosmic radiation (SCR). In addition, the Earth is exposed occasionally to burstsof energetic particles from the Sun (SPEs). GCR is mostly protons (85 %) with anenergy fluence distribution that extends from 106 electron volts (eV) to more than
1020 eV. These high-energy particles are a particular characteristic of cosmic
radiation, and contribute greatly to the dose. Protons with energies generally below
106 eV constitute 99% of SCR. GCR and SCR are commonly referred to as primarycosmic radiation (UNSCEAR, 2008; ICRU 2010).
(15) GCR interacts with the atomic constituents of the atmosphere, producing acascade of interactions and secondary reaction products that contribute to cosmic
radiation exposure (Fig. 1). These decrease in intensity with depth in the atmosphere,
from aircraft altitudes to ground level. The decrease is almost linear between 16 and8 kilometres of altitude: – 1.5 µSv h-1 km-1 (EC, 2004).
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496

497
498
499
500
501
502
503
504
505
506
507
508
509
510

511
512
513
514
515
516
517
518

Fig. 1. Cascade of secondary cosmic radiation, µ: muon, e-: electron, e+: positron, γ: photon,n: neutron, p: proton, π: pion (Rühm, 2012).

(16) Since the particles making up GCR are electrically charged, they can beaffected by the magnetic field of the Sun’s solar wind – the plasma of protons andelectrons from the solar corona that generate a magnetic field throughout the solar
system. The magnetic fields deflect the low-energy GCR that would otherwise enter
the Earth’s atmosphere. The solar wind varies with the Sun’s 11-year solar cycle,
and causes variations in the magnetic field. Close to the Earth’s orbit, GCR is at a
maximum during solar minimum activity, and GCR is at a minimum when the Sun’s
activity is greatest with sunspots, flares and coronal mass ejections (Fig. 2).

Fig. 2. The anti-correlation between the activity of the Sun (expressed as the number ofsunspots– blue curve) and the cosmic radiation exposure (expressed as the monthly average
neutron counts– black curve) from 1964 to 2014 (Paris-Meudon Observatory data).

(17) Paths of cosmic radiation particles are also bent as they cross the magnetic
field of the Earth, which acts as a partial shield against charged particles. Near the
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520
521
522
523
524
525

526
527
528
529
530
531
532
533
534
535
536
537
538

equator, where the geomagnetic field is nearly parallel to the ground, fewer particles
reach lower altitudes: the magnetic shielding effect is greater. Near the magnetic
poles, where the geomagnetic field is nearly vertical to the ground, the maximum
number of primary cosmic radiation particles can reach the atmosphere and generatesecondary radiation that penetrates to aviation altitudes. Thus, rates of cosmic
radiation exposure are higher in polar regions, and lower near the equator (Fig. 3).

Fig. 3. Geomagnetic shielding of cosmic radiation: Ambient dose rate by latitude andlongitude at 11 km altitude in December 2002 (Frasch, 2012).

(18) In summary, the cosmic radiation field in aircraft is modulated by altitude,
geomagnetic latitude, and solar cycle. At normal aircraft altitudes and at the equator,
the electrons/positrons and neutrons are the larger components in dose, followed byprotons. In contrast, at higher latitudes, the dose comes mostly from neutrons (Table
1). Additionally, at higher altitudes, nuclei heavier than protons (e.g. Fe) start tocontribute.
Table1. Contributions to cosmic radiation by its ambient dose equivalent component
according to latitude (at the altitude of 12,000 metres and at solar minimum) (EC, 2004).
Component

EquatorHigh latitude

539
540

Muons
5%
3%
Electrons/positrons
38 %
14 %
Neutrons *
37 %
64 %
Protons
12 %14 %Photons
8%
5%* The radiation weighting factors for neutrons used in the computation of dose vary as acontinuous function of neutron energy (ICRP, 2007).

541

2.3. Solar eruptions

542
543
544
545

(19) Exceptional high levels of radiation can occur from SPEs. The mean energyof the particles of SPEs – mainly protons – is generally below 100 MeV. Neutronsand γ rays may also be associated with these events (Bramlitt, 2014). Only a small
number of SPEs, about one per year, have significantly higher proton energies and17

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
546
547
548
549

can be observed by neutron monitors on the ground. These SPEs can cause increases
in dose rates at aviation altitudes. Fig. 4 gives the daily proton fluence observed by asatellite in April 1989; the solar eruption of the 10 April is easily observable.
3,00E+08

Proton fluence(proton/cm2/day/sr)

2,50E+08

2,00E+08

1,50E+08

1,00E+08

5,01E+07
days
1,00E+05
1

550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579

6

11

16

21

26

31

Figure 4. Daily proton fluence between 1 and 30 April 1989 (data from GOES-7 satellite,
National Atmospheric and Astronautics Administration).

(20) At present, it is almost impossible to estimate in advance the dose of an
SPE with any precision. The calculation of the doses to aircraft crew for the elevatedeffective dose rates in the event of an SPE is usually made retrospectively using
results from ground-level neutron monitors, or in exceptional cases, with on-board
measurements. The calculated dose rate can be quite substantial, but is characterisedwith associated large uncertainties of the order of factor 5 or more according toresults obtained by EURADOS Working Group 11 (EC, 2004). According to Lantos
and Fuller (2003), 64 SPEs were observed from 1942, and only 18 of them wereassociated with a significant likelihood of an increase in the effective dose rate ofaircraft crew of more than 30 µSv.h-1at 12,000 metres (like the SPE in April 1989)
and only 4 by more than 1 mSv.h-1 at 12,000 metres. Given their low frequency andthe level of individual dose involved, the contribution of SPEs to the total lifetime
exposure of aircraft crew to cosmic radiation is therefore marginal.
(21) The Commission is also aware that some concerns have recently beenraised about the potential exposure of aircraft crew and passengers to flashes of γrays produced in the atmosphere on the occasion of thunderstorms. Thisphenomenon, which is not related to cosmic radiation, was first observed by the
National Aeronautics and Space Administration in 1991. These flashes named“Terrestrial Gamma Flashes” (TGF) appear to occur at flight altitude and last a few
milliseconds with energy up to 20 MeV. The details of their mechanism of
production are uncertain, but the γ rays are presumably produced by electrons
accelerated by lighting and travelling close to the speed of light and colliding withatoms in the atmosphere (Dwyer, 2012). There is currently no element to assess thepotential exposure of aircraft crew and passengers associated with TGF. It should
also be noted that pilots systematically avoid thunderstorms for reasons of flightsafety.
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2.4. Assessment of individual exposure in aircraft

581
582
583
584
585
586
587
588
589
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591
592

(22) Individual exposure in aircraft can be estimated relatively easily withcomputer programmes. Indeed, the cosmic radiation field in an airplane is to a large
extent uniform: for a given flight, the exposure of different individuals is similar(Battistoni et al., 2005). For most of the computer programmes, the atmosphere isdivided into cubes through which the aircraft flies; the mean effective dose rate in a
cube depends on altitude, geomagnetic latitude and solar modulation. The dosewhen crossing a cube is the product of the dose rate with the time needed by theplane to cross the cube (Fig. 5), which depends on the standard flight profile. The
standard flight profile between two airports can differ from the actual flight profile,mainly because of weather conditions, but the impact on the dose is not consideredsignificant (Van Dijk, 2003).

LatitudeLongitude!!

Altitude

Flight profile
Dose = dose rate x time

593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617

Fig. 5. Typical mode of calculation of dose from cosmic radiation used by computer codes(Bottollier Depois, 2007).

(23) Computer codes that evaluate dose rates in airplanes can be validated andconsolidated by measurements of ambient dose rates in the aircraft. For example, inGermany, two passenger aircrafts were equipped with ambient dose rate meters for aperiod of 4 years in order to validate the calculation programmes used for official
dose calculation (Frasch, 2014). Details of the determination of ambient dose rate
are discussed in various consensus standards, for example in European Commission(EC, 2004) and the International Organization for Standardization (ISO) standards
ISO 20785 parts 1 to 3 (ISO, 2012).
(24) The EC has published a compilation of measured and calculated ambient
dose equivalent rates covering the time period from 1993 to 2003 (EC, 2004). These
data are the major basis for the analysis leading to the specification of reference
values of ambient dose equivalent given in a joint ICRP and ICRU Report (ICRU,
2010). These reference values can be used to check the conformity of the routine
procedure for the assessment of aircraft crew doses.
(25) Monitoring of occupationally exposed individuals in aircraft has been
recommended by ICRP in various previous publications (ICRP, 1997, 2007).
Because individual doses can be properly estimated retrospectively, the Commission
continues to recommend the use of validated computer codes, instead of using
measurement devices (dosimeters and other instruments) to monitor individual
exposure in aviation.
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619
620
621
622
623
624
625

(26) As an example, the effective doses for three flight routes estimated with thesoftware SIEVERT1 (based on the EPCARD code, Mares, 2009; Schraube 2002–
and available at http://www.sievert-system.org) can be found in Table 2. One cannotice that the value of the dose rate for the trans-equatorial route is the lowest.
Other examples of doses can be found in Appendix A.
Table 2. Example of effective dose calculated for different flight routes (for flights during
15 March 2013).
Total effective doseType of flight
Dose rate (µSv/h)(µSv)
Transatlantic flight:
Paris – New York60
6.8
Trans-equatorial flight:
Colombo – Jakarta
Transpolar flight:
Beijing – Chicago

9.7

2

82

6.8

626

627

2.5. Exposure of aircraft crew

628
629
630
631
632
633
634
635
636
637
638
639
640

(27) Data presented in the United Nations Scientific Committee on the Effectsof Atomic Radiation (UNSCEAR) 2008 report (UNSCEAR, 2008) indicate that therange of average annual effective dose for aircraft crew is of the order of a few mSv(from 1.2 to 5 depending on country) with a maximum value of about 6-7 mSv. The
average annual effective dose is highly dependent of the average annual flight time:of the order of 600 h in European countries and 900 h in the USA.
(28) A review of the exposure of aircraft crew in Europe (Andresz, 2015)
indicates that the average annual effective dose varies from 1 mSv for the airline of
the Czech Republic to 2.5 mSv for airlines from both Finland and Sweden. The
highest maximum annual effective dose is about 6-7 mSv for airlines from Denmark,Germany and Finland (Fig. 6). Apart from exceptional circumstances, aircraft crewreceive exposures of less than 10 mSv per year.

1

Reference to a particular software programme is for illustrative purposes, and does not constitute an ICRP
endorsement of this, or any similar codes.

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8

Annual effective dose (mSv)

7
6
5
4
3
2
1
0
Belgium(2009)

641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656

657
658
659
660
661
662
663
664
665

Czech
Republic

Denmark(2009)

Finland(2009)

France(2009)

Germany(2009)

Average annual dose

Lithuania(2009)

Slovenia(2009)

Sweden(2008)

The
UnitedNetherlands Kingdom(2007)

Maximum annual dose

Fig. 6. Average and maximum annual effective dose for crew members in European
countries (EAN, 2012).

(29) Aircraft crew exposure is also an important component of annual collective
effective dose. According to UNSCEAR (2008), the total collective annual effective
dose of aircraft crew in the world is of the order of 800 man Sv. The collective
effective dose per country is largely dependent on the size of the national airline
companies and the annual flying time. The collective effective dose can reach morethan 50 man Sv per year for certain countries (for example, 78.5 man Sv forGermany in 2012). Such collective doses are by far the main contributor to thecollective occupational exposure. Table 3 represents the occupational collective
exposure for aircraft crew in some countries.
Table 3. Collective dose for aircraft crew (UNSCEAR, 2008)
Monitored
Country
individuals
Denmark
3,990
Finland2,520
Germany
31,000Lithuania
160
The Netherland
12,500
United Kingdom
40,000
United States of America
150,000

Collective dose (man Sv)
6.8
4.2
60.0
0.2
17.0
80.0
Not available(30) The distribution of doses received by aircraft crew results from the
combination of two Gaussian distributions: one for cockpit crew and the other forcabin crew (Fig. 7). Such exposure profiles are typical of a population that has arelatively uniform exposure at levels sufficiently low that has not warranted theapplication of controls. By comparison, the underlying exposure conditions in the
nuclear industry are typically much more variable than those in aviation. This fact
and the application of the optimisation of protection typically result in a much moreskewed distribution of doses (e.g. approaching a lognormal distribution).
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10000
9000
8000

Aircraft Crews (N=36,410)

Number of people

7000

Nuclear Industry Workers (N=18,694)

6000
5000
4000
3000
2000
1000
0

0-0,5 0,5-1 1-1,5 1,5-2 2-2,5 2,5-3 3-3,5 3,5-4 4-4,5 4,5-5 5-5,5 5,5-6 6-6,5 6,5-7 7-7,5 7,5-8
Dose interval (mSv)

>8

667
668
669

Fig. 7. Distribution of dose for aircraft crew and nuclear industry workers in Germany in2009 (Frasch, 2012).

670

2.6. Epidemiological studies of aircraft crew

671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693

(31) Epidemiological studies of aircraft crew have been conducted over the last
20 years (for example, as reviewed in Zeeb, 2012). The early studies were
investigations of pilots from Canada, the United Kingdom and Japan. With regards
to cancer, pilots, almost completely composed of males, showed reduced cancer
mortality when compared with the general population – this reduction is often
observed in occupational cohorts as a healthy worker effect. But, certain specifictypes of cancers, namely melanoma and brain cancer, seem elevated in the aircraftcrew population (Zeeb, 2012).
(32) A second generation of investigations in the 1990s included a larger set ofEuropean and American studies. As was observed previously, cancer mortality ofpilots was lower than that of the general population and some cancers (melanoma
and brain cancer) showed “a very moderate excess risk”. A study also showed aslightly increased risk of cataracts for female cabin crew (80 % of the cabin crew,
essentially represented by women before pregnancy) and “a very moderate elevation”
of breast cancer mortality compared with the general population (Rafnsson, 2005).
(33) UNSCEAR (2006) stated that evidence has been found for consistentexcess risk of melanoma, non-melanoma skin cancer and breast cancer. But, no
relation with the duration of employment was found, and without the information on
individual radiation dose, it is difficult to correlate the observed excess risks toionising radiation, or to solar ultraviolet light (UV) exposure. A recent paper showsthat breast cancer incidence is not associated with cosmic radiation exposure, whichmight be explained by lower parity and older age at first birth (Schubauer-Berigan,
2015).
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696
697
698
699
700
701
702
703
704
705
706
707
708
709

(34) A study on the mortality of commercial aircraft crew members followed
94,000 Europeans and Americans for an average of 22 years (Hammer et al., 2014).
This study showed an overall reduction of cancer and cardiovascular mortality
compared to the general population. An elevated mortality from skin melanoma wasobserved for cockpit crew, but apparently not directly related to occupational
exposure and attributable to light skin and sunbathing. Contrary to other studies, noelevation of breast cancer for female aircraft crew was found, but an increased
mortality from prostate cancer in male aircraft crew was observed. Generally, themortality from radiation-related cancers was lower than expected for aircraft crew.
The authors recommend further analysis as aircraft crew are exposed to a number ofpotential risk factors besides ionising radiation: stress, disruption of the circadianrhythm, exposure to jet fuel, etc.
(35) In conclusion, the available epidemiological data show no clear relation
between the duration of work of aircraft crew and their corresponding doses fromcosmic radiation, with an excess risk of radiation-related cancers.

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710
711

3. THE COMMISSION’S SYSTEM OF PROTECTION FOR PASSENGERS
AND AIRCRAFT CREW

712
713
714
715
716
717
718
719

(36) The Commission’s system of radiological protection of humans is
described in Publication 103 2 (ICRP, 2007). According to its paragraph 44, it“applies to all radiation exposures from any source, regardless of its size andorigin.” In particular, according to paragraph 45, the Commission’s
Recommendations cover exposures to both natural and man-made sources.
(37) The philosophy of Publication 103 is to recommend a consistent approach
for all type of exposure situations, with the central consideration being optimisation
process below appropriate dose restrictions.

720

3.1. Type of exposure situations and categories of exposure721

3.1.1. Type of exposure situations

722
723
724
725
726
727
728
729
730
731
732
733

(38) The Commission defines an exposure situation as a network that begins
with a natural or man-made radiation source, the transfer of the radiation orradioactive materials through various pathways, and the resulting exposure ofindividuals (paragraph 169 of Publication 103). Protection can be achieved bytaking action at the source, or at points in the exposure pathways, and occasionallyby modifying the location, the time of exposure and the protection of the exposed
individuals. For convenience, the environmental pathway is usually taken to include
the link between the source of exposure and the individuals receiving doses.
(39) According to paragraph 176 of Publication 103 (ICRP, 2007), theCommission intends its Recommendations to be applied to all controllable sourcesin the following three types of exposure situations, which address all conceivable
circumstances:• Existing exposure situations are exposure situations resulting from sourcesthat already exist when a decision to control the resulting exposure is taken.
Characterisation of exposures is a prerequisite for their control;• Planned exposure situations are situations resulting from the deliberate
introduction and operation of sources. Exposures can be anticipated andfully controlled; and• Emergency exposure situations are situations that may occur during theoperation of a planned situation in case of loss of control of the source, orfrom any unexpected event involving an uncontrolled source. Urgent
action is necessary in order to avoid or reduce undesirable exposures.
(40) The Commission views human exposures in aviation resulting from cosmic
radiation as an existing exposure situation. The source already exists, and any
protection decisions are made in that context to control the exposure. The pathway
from the radiation source is outer space, the atmosphere and the aircraft structure,and the exposed individuals are the aircraft crew and passengers. Action to control
exposures can only be implemented by changing the exposure conditions of the
exposed individuals. The Commission considers that SPEs, even major ones, arepart of existing exposure situations given their infrequent presence in the flight

734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751

2

At the time of the publication of the present report, the Commission was revising the glossary enclosed in the
Publication 103 because of some imperfections and inconsistencies with the text so that the report is referring to
the text of Publication 103 rather than to its glossary.

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753
754

environment, and the resulting contribution to the exposure of aircraft crew andpassengers (see paragraphs19 and 20).

755

3.1.2. Categories of exposure

756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772

(41) The Commission distinguishes between three categories of exposure:
occupational, medical and public exposures. Occupational exposure is radiation
exposure of workers incurred as a result of their work. However, because of theubiquity of radiation, the Commission traditionally limits the definition of‘occupational exposures’ to radiation exposures incurred at work as a result ofsituations that can reasonably be regarded as being the responsibility of theoperating management. Medical exposure is the exposure of patients in the course of
medical diagnosis and treatment. Public exposure encompasses all exposures otherthan occupational exposures and medical exposures.
(42) In aviation, the exposed population to cosmic radiation includes occasional
flyers, frequent flyers - for personal reasons and for professional duties - and aircraftcrew. The Commission maintains its view that the exposures of occasional andfrequent flyers are public exposure, and the exposure of the particular group of
aircraft crew is occupational exposure (ICRP, 1991, 1997, 2007). However, theCommission is now proposing a graded approach for the protection of these threegroups, taking into account the level of exposure expected for each of them and the
responsibilities that need to be considered (Section 4.2).

773

3.2. Justification of protection strategies

774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796

(43) The principle of justification is one of the two fundamental source related
principles that apply to all exposure situations. The recommendation in Publication
103, paragraph 203, requires, through the principle of justification, that any decisionthat alters the radiation exposure situation should do more good than harm. The
Commission goes on to emphasise that for existing exposure situations, thejustification principle is applied in making the decision as to whether to take action
to reduce exposure and avert further additional ones. Any decision will always havesome disadvantages and should be justified in the sense that it should do more goodthan harm. In these circumstances, as stated in paragraph 207 of Publication 103, theprinciple of justification is applied in aviation in making the decision as to whether
or not to implement a protection strategy against cosmic radiation exposure.
(44) After characterising the situation, the responsibility for judging thejustification usually falls on governments or other national authorities to ensure thatan overall benefit results, in the broadest sense to society, and thus not necessarily toeach individual. However, input to the justification decision may include many
aspects that could be informed by users or other organisations or persons outside of
the government or national authority. In this context, radiological protection
considerations will serve as input to the broader decision process.
(45) Although possibilities to control exposures in aircraft are limited (Section4.1), the Commission considers that the implementation of a protection strategy isjustified, especially for aircraft crew, given that this is one of the mostoccupationally exposed population both in terms of mean individual and collective
effective doses (Section 2.5).
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3.3. Optimisation of protection

798
799
800
801
802
803
804
805
806
807
808
809
810
811

(46) When decisions have been made regarding the justification of
implementing a protection strategy, then the optimisation of protection becomes thedriving principle to select the most effective actions for protecting the exposed
individuals.
(47) Optimisation is the second source-related principle that applies to all
exposure situations and is central to the system of radiological protection. It isdefined by the Commission as the process to keep the magnitude of individual doses,
the number of people exposed, and the likelihood of incurring exposures, as low asreasonably achievable (ALARA) below appropriate individual dose criteria, taking
into account economic and societal factors. This means that the level of protection
should be the best under the prevailing circumstances. In order to avoid serious
inequity in the individual dose distribution, the Commission recommends using
individual dose criteria (reference levels and dose constraints) in the optimisation
process (paragraph 226 of Publication 103).

812

3.3.1. Reference levels

813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842

(48) In existing exposure situations, the reference level represents the dose
above which it is judged to be inappropriate to allow exposures to occur, for which
protective actions should therefore be implemented. Reference levels are guides forselecting protective actions in the optimisation process in order to maintainindividual doses as low as reasonably achievable taking into account economic andsocietal factors, and thus prevent and reduce inequities in the dose distribution. As
such, reference levels are also a benchmark against which protective actions can be
judged retrospectively.
(49) For existing exposure situations, the Commission recommends settingreference levels within the 1 to 20 mSv/year band as presented in Table 5 of
Publication 103. In this band, the sources or the pathways can generally becontrolled, and individuals receive direct benefits from the activities associated withthe exposure situation, but not necessarily from the exposure itself. In aviation,passengers receive direct benefits from flying; travelling rapidly with comfort andsecurity. Like for other situations of occupational exposure to ionising radiation,
aircraft crew receive direct benefit from their employment.
(50) For a particular exposure situation, the Commission recommends that the
selection of the value of the reference level should be made based upon theprevailing circumstances (paragraph 234 of Publication 103). This selection should
be made considering the individual dose distribution with the objective to identify
those exposures that warrant specific attention. For the protection against cosmic
radiation in aviation, the Commission recommends that a reference level cangenerally be selected in the 5 to 10 mSv/year range.
(51) The selected reference value is not a dose limit, but represents the level ofdose below which exposure should be maintained and reduced as low as reasonably
achievable taking into account economic and societal factors. The principle ofapplication of individual dose limits only applies in planned exposure situations(paragraph 203 of Publication 103). Nevertheless, some regulatory bodies may
decide to introduce occupational dose limits to aircraft crew as a procedure to
impose legally binding values.

843

3.3.2. The optimisation process
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844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862

(52) In practice, optimisation of protection in existing exposure situations is
implemented through a process that involves (a) the assessment of the exposure
situation taking into account economic and societal factors; (b) identification of thepossible protective options to maintain or reduce the exposure to as low asreasonably achievable; (c) the selection and implementation of the most appropriate
protective options under the prevailing circumstances; and (d) the regular review ofthe exposure situation to evaluate if there is a need for corrective actions, or if newopportunities for improving protection have emerged. In this iterative process, theCommission considers that the search for equity in the distribution of individual
exposures (i.e. the objective to limit the possibility that some individuals may besubject to much more exposure than the average in a group exposed under similar
circumstances), and the improvement of radiological protection culture areimportant aspects (ICRP, 2006). When optimising protection, the Commission also
recommends “the need to account for the views and concerns of stakeholders”(ICRP, 2007).
(53) Detailed advice of the Commission on how to apply the optimisation
principle in practice has been provided earlier (ICRP, 1983, 1989, 1991b, 2006a),and remains valid.

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863

4. IMPLEMENTATION OF THE SYSTEM OF PROTECTION

864

4.1. Protective actions

865
866
867
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869
870
871
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874
875
876
877
878
879
880
881
882
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889
890
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900
901
902
903
904

(54) The review of potential protective actions to control exposure in aviationshows that there is little room to manoeuvre. In Publication 75 (ICRP, 1977), theCommission noted that “the control of [cosmic radiation] exposure is mainly
ensured by restrictions on the flying time and route selection”. Indeed, shielding ofaircraft (fuselage) is not a feasible option. For example, a 30 g cm-2 shielding isnecessary to achieve a reduction in the dose rate at 12,000 metres by only 20%.
Even flying time limitation and route selection are difficult actions to implement.
• Flying time limitation. Since the dose depends on flight time, work
planning of aircraft crew is a means to limit time in air. However, limiting
flight time of aircraft crew increases the number of people exposed, and its
implementation at large scale may raise societal and economic problems.
• Route selection. It is conceivable to limit exposure by choosing the flightroute and acting on altitude and latitude.
o Altitude. As described in Section 2.2, the Earth’s atmospheric layer
provides significant shielding from cosmic radiation. Optimisation
by flight level is a matter of fine-tuning taking into account factors
such as weather condition and air traffic but also costs. For example,
it is estimated that a reduction of flight altitude by 1,300 metres can
reduce dose by 30%. However, this change in altitude increases therisk of incident, and also fuel consumption and cost by 2% (Hammer
and Blettner, 2014).
o Latitude. As also described in Section 2.2, the Earth’s magnetic field
deflects many cosmic radiation particles that would otherwise reachground level, and this effect is most effective at the equator anddecreases at higher latitudes. However, optimisation by latitude, inparticular re-routing polar flights, increases flight distance, time, andalso cost.
(55) Regarding the exposure during an SPE, it could be envisaged to reduce thealtitude of flying aircrafts and delay flights that have yet to take off. The
implementation of these actions requires the use of sophisticated information
systems, which currently remain difficult to develop given technical andorganisational considerations. It can also disrupt air traffic, which is already tightly
scheduled, and increase the potential for incidents.
(56) In view of the current options for the control of exposure during flights, theCommission continues to emphasise that the main action to control exposures inaviation is to adapt the flight schedules of the most exposed individuals by
combining flight time and route selection. For the protection in aviation, theCommission is now recommending a graded approach according to the level of
exposure that individuals are likely to receive depending on the frequency of theirflights.

905

4.2. Graded approach

906
907

(57) Important consideration for the protection from cosmic radiation in aviation
are the circumstances requiring air travel, the frequency with which an individual28

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922

may be exposed and the responsibilities at stake. In this regard, it is important todistinguish between people flying on their own initiative or in the context of theirwork at the request of their operating management. Because of these considerations,the Commission is now adopting a graded approach for the various categories of
persons exposed in aviation.
(58) For the vast majority of people, using air transport is an occasional event,and exposure to cosmic radiation is very low (occasional flyers). The exposure
becomes higher for a minority of passengers using aircraft frequently, either
privately or in the course of their work (frequent flyers). For this minority ofpassengers, simple ways can be used by these individuals to assess their exposuresand give them the opportunity to understand their exposure. For aircraft crew who
generally receive more significant doses, an appropriate management of protection
is required, based on a regular monitoring of all individual doses and the adaptationof the flight schedules for those individuals with doses approaching the reference
level adopted by the operating management.

923

4.2.1. Occasional flyers

924
925
926
927
928
929
930
931
932

(59) The Commission is of the view that exposure received by occasional flyers
is negligible and does not warrant the introduction of protection measures.
(60) However, for the sake of transparency and applying the right to know
principle, the Commission recommends that general information about cosmic
radiation should be made available for all passengers. For example, this information
could be posted on airlines’ websites. These websites could make the people awareof the free and validated calculators that estimate flight doses, such as with
EPCARD, SIEVERT, etc. Annex A gives estimated effective doses for some typicalinternational flight routes.

933

4.2.2. Frequent flyers for personal preference and for professional duties

934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954

(61) Groups of individuals may use aircrafts frequently for their personal needs
or convenience. Other individuals fly frequently at the request of their operating
management. Most frequent flyers are not exposed to cosmic radiation under thesame circumstances as aircraft crew (e.g. in terms of exposure, frequency of flights,
and degree of choice). Therefore, the Commission recommends that the exposure of
frequent flyers be considered as public exposure (see paragraph 43), and that
individuals exposed be treated in the same way as occasional flyers. The
Commission recommends that general information about cosmic radiation be madeavailable to these individuals.
(62) In addition, the Commission encourages frequent flyers who may beconcerned by their cosmic radiation exposure to assess their personal exposure using
freely available dose calculators, in order to be aware of their exposure and adapt
their flight frequency as they feel the need.
(63) Among the frequent flyers for professional duties, a very small fraction is
exposed under circumstances, which result in exposures comparable to aircraft crew.
This may be the case, for example, for couriers transporting documents andmaterials, or air marshals. The Commission recommends that the exposure of thesefrequent flyers be managed in a manner similar to the requirements applying toaircraft crew. It is not the intention of the Commission to provide an exhaustive listof the professions at stake, and the decision to consider these frequent flyers as
occupationally exposed should be taken on a case-by-case basis according to the29

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
955
956
957
958

prevailing circumstances. This may result from an individual assessing their
exposure, and using this information to engage their employer in a dialogue, if
appropriate. A decision should result from a process involving all concerned
stakeholders.

959

4.2.3. Aircraft crew

960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983

(64) The Commission recommends that the airlines management inform theconcerned aircraft crew about radiation and cosmic exposure through educational
programmes. Information could also be provided to crew at safety meetings, andshould be given emphasis in line with other safety issues.
(65) Like for any occupationally exposed worker, the Commission recommends
that annual effective dose of each aircraft crew be assessed. The annual effective
dose can be derived from the staff-roster and typical effective dose rates using
dedicated computer codes. The Commission recommends the occasional use of onboard ambient monitoring for verification and validation of dose calculations (ICRU,
2010). Because the contribution of SPEs to the total dose is marginal, theCommission does not recommend the use of specific monitoring systems such asreal time alert systems.
(66) The Commission also recommends that aircraft crew doses should berecorded, and that annual and cumulative individual doses should be made available
as per request from the individual. To facilitate potential epidemiological studies,
this information should be kept for sufficient time.
(67) Aircraft crew routinely undergo medical examination. The Commission
considers that exposure to cosmic radiation does not require specific additional
medical examination. Generally, routine medical examination is an opportunity toengage a dialogue between a worker and a physician on the topic of cosmic radiation
exposure.
(68) When judged appropriate and to respect the selected dose reference level,
the operating management may adjust, in consultation with the concerned aircraft
crew, their flight schedule (frequency and destination).

984

4.2.4. Summary

985
986
987
988
989

(69) Table 4 lists the recommendations of the Commission regarding the cosmic
radiation exposure of the individuals.
Table 4. Recommendations of the Commission for the individuals exposed to cosmic
radiation in aviation.
Exposedindividuals
Referencelevel to be
selected in
the 5–10
mSv/yearband

Occasional flyers

Frequent
FlyersRecommendations

Categories
of exposure• General information• General information• Self-assessment of doses• Adjustment of flight frequency as

30

Public*DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
appropriate

Aircraft
crew

•
•
•
•
•

Individual information
Assessment of individual doses
Recording of individual doses
No specific additional medical surveillance
Adjustment of flight schedules asappropriate

Occupational

990
991

*Some groups of frequent flyers may be managed in a manner similar to those occupationally992

4.3. Protection of embryo and fetus

993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017

(70) In Publication 82 (ICRP, 1999), the Commission concluded that prenatal
exposure in the case of an existing exposure situation does not require protective
actions other than those aimed for the general population. The Commission does nottherefore believe that actions to adjust flight schedules of pregnant women will benecessary. Women who fly frequently and may be or expect to be pregnant should
be provided with sufficient information to make informed judgments regarding theflight schedule and any adjustment they may which to consider.
(71) Regarding the occupationally exposed aircraft crew, it is the Commission’s
policy that the methods of protection at work for pregnant women should provide alevel of protection for the embryo/fetus broadly similar to that provided for membersof the public. The Commission recommended in paragraph 186 of Publication 103(ICRP, 2007): “Once an employer has been notified of a pregnancy, additional
protection of the embryo/fetus should be considered. The working conditions of apregnant worker, after declaration of pregnancy, should be such as to ensure thatthe additional dose to the embryo/fetus would not exceed about 1 mSv during theremainder of the pregnancy”.
(72) Generally, female workers have to declare their pregnancy to theiremployer after a few months of pregnancy. In some countries, the decision is avoluntary matter for the individuals. Irrespective of these differences, pregnant crew
may receive more than a millisievert before declaring the pregnancy. To encourage
the timely declaration of pregnancy, the Commission recommends that female
aircraft crew and frequent flyers be informed about the risk for the embryo/fetus
from exposure to cosmic radiation. After the declaration, the operating managementfor occupationally exposed individuals should have provision in place to adjust
duties during the remainder of the pregnancy.

1018

4.4. Information of the general public and stakeholder engagement

1019
1020
1021
1022
1023

(73) Aside from experienced scientists, experts and professionals trained inradiological protection, citizens are usually not well informed about radiation andtheir potential health effects. On the matter of exposure to cosmic radiation, apartfrom most of the aircraft crew, few people among the general public are aware ofthis exposure, although they are constantly exposed to cosmic radiation in everyday

exposed on a case-by-case basis according to the prevailing circumstances.

31

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066

life on the ground and at an elevated level when travelling in aircraft. However, in
recent years, there has been growing information on cosmic phenomena andparticularly solar flares (SPE), disseminated by space and weather organisations, andrelayed by media; occasionally giving rise to alerts of airlines. This information has
awakened the attention of some passengers to cosmic radiation, but also raisedquestions and sometimes concerns among frequent flyers and aircraft crew about therisk associated with cosmic radiation exposure.
(74) In accordance with the right to know principle, which states that people
have the right to be informed about the potential risks that they may be exposed intheir daily life, the Commission encourages national authorities, airline companies,
consumer unions and travel agencies to disseminate general information about
cosmic radiation associated with aviation. This information must be easily
accessible and present the origins of cosmic radiation as well as the influence ofaltitude, latitude and solar cycle, and indicate typical doses associated with a set of
traditional flight routes and the potential of receiving significant exposures when
flying frequently in case of a rare but intense SPE.
(75) As mentioned in Sections 2.4 and 4.2, several easy-to-use tools have been
made available on the internet in recent years, which allow dose calculations
associated with all possible flights.
(76) The Commission recommends that the general information on cosmic
radiation should be such that the messages are accurate, informative, and responsive
to the nature of the concerns and the challenges in terms of radiological protection
according to the situation. It is not the Commission’s intent to suggest that cosmic
radiation be viewed out of proportion with other risks or considerations, but instead,to foster a more inclusive view of all risks so that individuals can make informed
decisions.
(77) In this perspective, comparison with other exposure situations to naturaland man-made radiation sources may be useful (e.g. a flight London – New York
gives the same effective dose as spending 10 days on holiday in high mountainregions) and should be made accessible as part of the general information on cosmic
radiation. However, such comparisons must be undertaken with care, because theperception and tolerability of risk depend largely on the characteristics of thesituation, and in particular, the benefit for the individuals of the activities that lead tothe exposures.
(78) The Commission considers that, as regards to the protection against cosmic
radiation in aviation, passengers who are not occupationally exposed must remain
accountable for their choices, but that these choices should be made knowingly
based on relevant information without bias. The decision by individuals to reduce
the frequency of their flights will be based on personal considerations for which therisk of exposure to cosmic radiation is only one element among many others. Finally,
it is up to the people who take the risk to judge about its tolerability based on
accurate information, and to make decisions for their own protection.

32

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
1067

5. CONCLUSION

1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102

(79) The Earth is continuously bombarded from particles coming from deep
space and the Sun. The atmosphere and the Earth’s geomagnetic field provide a
sufficient shielding to make exposure at ground level not of particular concern but
exposure to cosmic radiation increases with altitude. This existing exposure situation
is experienced by millions of travellers: passengers for personal reasons, or onrequest of their operating management, and aircraft crew who are one of the mosthighly exposed occupational populations.
(80) The Commission notes that flying occasionally only contributes to a verysmall increment of the dose received annually due to natural background radiation at
ground level, and does not warrant the introduction of protection measures. It is
recognised that some passengers may, for personal and very different reasons, beconcerned about exposure to cosmic radiation. The Commission thus recommends
the dissemination of relevant information to allow them to make informed decisions.
(81) For frequent flyers for personal preference and professional duties, theCommission also recommends the dissemination of relevant information andmoreover the self-assessment of their exposure in order to adjust flight frequency as
appropriate. For particular groups of frequent flyer for professional duties who areexposed under flight durations similar to those of aircraft crew, the Commission
recommends that they engage in discussions with their organisations in order tomanage their exposure with requirements similar to those applying to aircraft crew.
(82) For the protection of aircraft crew, the Commission maintains its previous
recommendations, and introduces the use of a reference level to be selected byoperating managements in the 5 to 10 mSv/year range. The specific level selectedshould take into account the prevailing circumstances so that the value canmeaningfully contribute to the optimisation process. The margins for manoeuvre to
reduce exposures from cosmic radiation are very small, and the only effective option
is to reduce flight time when doses are approaching the selected reference level.
(83) With the above recommendations, the Commission expects to keep dosesof the most exposed individuals –aircraft crew and some frequent flyers– toreasonable levels. The Commission also anticipates that by raising the generalawareness of exposure to cosmic radiation in aviation. All involved stakeholders –occasional flyers, frequent flyers and aircraft crew – are encouraged to makeinformed decisions with regard to the exposures associated with flying byconsidering at the same time all the benefits they receive from air travel.

33

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCEAPPENDIX A.

1103
Effective doses are inmSv

Abu Dhabi(Emirates)

Abu Dhabi (Emirates)

1104
1105

COSMIC RADIATION EXPOSURE ASSOCIATED WITHSELECTED FLIGHT ROUTES

Johannes
burg

Kuala
LumpurLima

LondonMexico(city)

Moscow

New York(city)

Rio deJaneiro(city)

Tokyo

San
Francisco

Sydney

0.015

0.013

0.037

0.025

0.107

0.016

0.077

0.029

0.024

0.109

0.039

0.025

0.046

0.027

0.048

0.028

0.045

0.032

0.035

0.072

0.096

0.131

0.043

0.072

0.028

0.1

0.067

0.012

0.59

0.012

0.039

0.013

0.073

0.024

0.014

0.058

0.025

0.072

0.079

0.019

0.049

0.028

0.08

0.08

0.075

0.091

0.017

0.023

0.062

0.009

0.036

0.064

0.04

0.053

0.089

0.045

0.025

0.095

0.03

0.058

0.126

0.038

0.102

0.042

0.02

Johannesburg

0.015

Kuala Lumpur

0.013

0.025

Lima

0.037

0.046

0.131

London

0.025

0.027

0.043

0.0385

Mexico (city)

0.107

0.048

0.072

0.013

0.079

Moscow

0.016

0.028

0.028

0.073

0.019

0.091

New York (city)

0.077

0.1

0.1

0.024

0.049

0.017

0.064

Rio de Janeiro (city)

0.029

0.067

0.067

0.014

0.028

0.023

0.04

0.025

Tokyo

0.024

0.012

0.012

0.058

0.08

0.062

0.053

0.095

0.126

San Francisco

0.109

0.59

0.59

0.025

0.08

0.009

0.089

0.03

0.038

0.042

Sydney

0.039

0.012

0.012

0.072

0.075

0.036

0.045

0.058

0.102

0.02

0.033
0.033

Distance and flight-time were calculated with the HAVERSINE formula; effective doses are calculated for January 2012 using the software SIEVERT(http://www.sievert-system.org/index.html).

34

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153

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